So, in reality this people are just lacking the knowledge (faltos de conocimiento, I call them).

I found many explanations on the WEB, but the simplest is this one: "Agnostics claim either that it is not possible to have absolute or certain knowledge of the existence or nonexistence of God or gods; or, alternatively, that while individual certainty may be possible, they personally have no knowledge. Agnosticism in both cases involves some form of skepticism."